[Coco] some questions and thoughts..... and a return to being a COCO nut... <G>

[Gene Heskett]

On Thursday 19 June 2014 14:08:09 Chris Ahrendt did opine
And Gene did reply:
> I am getting back into the COCO... my original coco was a battleship
> grey 64MB coco 1 with 2 disk drives and a 300 baud modem.
> I should be receiving my coco 2 with 64MB and a FD-500 next week
> sometime. I have ordered the parts to do the drive wire cable.
> I was very active in the coco scene in the Washington DC area and ended
> up stopping when I moved back to Germany...
> 
> Now with all of that said... here comes the old timer / newbie
> questions...
> 
> I have been going through all of the archives on the various magazines
> (Rainbow, Hot Coco, etc).
> 
> The model I am getting is:
> 26-3127B which I read has the newer video chip that has lower case.
> The Floppy is a
> 26-3129 FD500
> I won't know if the drive has one or two drives in it till I get it. My
> thought is to replace the drive(s) if they are SSDD with a DS/DD drive
> and then a 720k 31/2" drive in the second bay.
> 
> So here are the questions:
> 
> 1. How do I turn on and keep the lower case on if indeed this model has
> the video chip with the lower case ability.
> 2. IF I want to use the drives as DS/DD  drives what needs to be done.
> I have read the drive tutorial and it is a bit confusing to me being
> an old timer. It used to be you had to have a new ROM burned or a
> non-Tandy drive controller.
> 3. One of the things I do remember liking was a friends setup (think it
> was a J&D) had the ability to hit the up arrow and repeat and edit the
> last command much like I do on Linux. and he was able to address the
> drives as single or double sided...  so would this just be a matter of
> getting the right prom and cable?
> 4.  I have read that the FD500's have issues with heat... is there
> anything that can be done to help that? any instructions?
> 5. Is there a way to set up the Coco so that I can used the drive wire
> and the floppy drives at the same time? IE use drive-wire as my gateway
> for printing / drives etc...
> 6. Is there anywhere that describes the drive-wire protocol?
> 
> I was looking at the archives here and one of the discussions was
> around a network controller for the Coco's why not instead use a
> Arduino with either a hard wire Ethernet or WiFi? I assume that there
> is some sort of handshake between the server and client that goes
> on...
> It would be real easy to pull a pin high from the arduino to let the
> coco know that a packet has been received.
> The limiting factor would be the bit banger if you used that .. It may
> be faster to interface via the cart and have a splitter one going to
> the disk
> controller and the other to the arduino connector.  The IP stack is
> built into the arduino so you would just need to write a simple arduino
> routine to talk to the drive wire client.
> If this works the drive-wire server could use the IP connection it
> already has to talk to the client. Question is does the server support
> multiple connections?
> 
> 7. I have seen several projects in the older coco's for 128k upgrade
> projects... is this worth it or should I just bite the bullet and buy a
> coco 3 for that?
> 8. If I install a board which does the inverted (light green on black
> (I prefer that)) would the characters still be lower case?
> 9. I have read also about the Hitachi upgrade to the coco... what would
> it buy me on a coco 2 or a coco 3? I am going to be using it for OS-9
> and some games.
> 10. If I do the composite  color mod and connected it up to a composite
> input on a LCD monitor would I get the artifact colors still?
> 11. Multi-pack.... I am thinking of getting one of these but have heard
> there is an issue with the PAL and the coco 3.

There is, the coco3 uses the $FF90-$FF9F range heavilty in its memory 
controller.  But the decoding in the MPI is not complete so while it 
officially responds to reads & writes to $FF7F, which is its slot 
selection circuitry, it also responds to the gime reads and writes at 
$FF9X.  Depending on the MPI, a gal upgrade, or another logic chip is 
added to disable any response to the $FF9X range.

Properly written software should not cause any problems in using a "fixed" 
MPI with any coco.

It does however present another problem when using an rs232 pack in the 
MPI.  The slot selection logic is actually 2 circuits, one doing the slot 
selection, and one steering the IRQ's from the slots on thru to the coco.

The fix for that is to locate the pullup R's that pull all pin 8's on the 
slots high, remove 3 of those R's, and wire all 4 pin 8's together so that 
an IRQ gets thru the otherwise blocking IRQ steering stuff. I don't know 
of rsdos interactions, but os9 can find the source of ANY interrupt in an 
absolute worst case of 150 microseconds, which is fast enough to never 
lose an incoming byte.

I found that, and fixed my MPI well before I had bought my first coco3.

>          There is a version A of the Multi-pack that works with the
> coco 3, does it work with coco 2's?
>          I get the pal fix from coco3.com and install the fix is it a
> one way trip and no longer useable by the coco 2?

It shouldn't effect it with a coco, any coco, as long as the software uses 
the correct $FF7F as the slot selection addr.  I've not run acrossany that 
did not use the correct address.

> 12. Will an X-pad (the big grey slate) work with either coco2 / 3 if
> its used through the Multi-pack?

I have one, and ISTR I had to change a small coil it it due to the coco3's 
2x faster clocking.  Essentially the same problem exists with the 
speech/sound pack.  It also needs a faster transistor for the same reason.

> 13. Is there anyone out there that would burn a eprom for a disk
> controller to add the HDB-Dos to the controller... or is it just as
> easy to boot off disk?

I believe Mark, at Cloud9north can do that.

> 14. what are some of the gotchas that I need to check with a vintage
> coco? 15. What are some of the things I should probably buy/build/
> find? 16.  Real Time clock... there was some talk of a plug in
> compatible (basically put it under the DOS prom) real time clock...
> does anyone have a instructable on this?

Those disk controllers with clocks, such as the TC^3, can be used. For 
OS-9, the clock module will need to be changed, but it should otherwise 
Just Work.

> 17. Is it worth building a high res joystick adapter to use or is it
> just limited to coco max use?
> 
> I am sure I will have more questions once she gets here.. thanks
> everyone....
> 
> Chris


Cheers, Gene Heskett
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